While looking for some other information, I came acrossa post on this South African VW site with these factory dyno charts for VW 1600CC engines: One with a single port head, one with a twin port head:
Single Port 1600CC engine below:
Dual port 1600CC below:
The scale of the two charts isn't the same. My reading (below) of the data from those charts (conversion factor used: 1 mkg = 7.23 lb-ft). The HP figures below are computed as: HP= Torque (ft lb) x RPM/5252 and don't exactly match the DIN HP as directly plotted from the dyno runs.
So, what is the most useful interpretation of this? Possibilities:
A) In the OEM Type 1 1600cc engine, the dual port has more maximum torque (and HP) than the single port heads at all RPMs. They are close in performance at 2200-2400 RPM (where the SP is near its peak), but the dual port performs significantly better above and below that. The torque curve on the DP engine is relatively flat from 1600 RPM to 3000 RPM. (This is pretty much a direct reading of the chart info.)
or
B) That data isn't applicable to Type 1 engines in aircraft (due to induction differences, different camshafts, etc). The single port performs better in aircraft, especially at low RPMs
or
C) At 1600cc dual port engines may provide more torque and power in aircraft installations, but single port heads are still preferable for other reasons (BSFC, strength, cooling, etc)
And, any implication for engines of larger displacement?
I'm pretty sure nothing here is new, but it is the first time I'd seen it.
Mark
Single Port 1600CC engine below:
Dual port 1600CC below:
The scale of the two charts isn't the same. My reading (below) of the data from those charts (conversion factor used: 1 mkg = 7.23 lb-ft). The HP figures below are computed as: HP= Torque (ft lb) x RPM/5252 and don't exactly match the DIN HP as directly plotted from the dyno runs.
RPM | Single Port Torque (mkg) | Dual Port Torque (mkg) | Single Port Torque (lb-ft) | Dual Port Torque (lb-ft) | Single Port HP | Dual Port HP |
1600 | 9.6 | 10.4 | 69 | 75 | 21.1 | 22.9 |
1800 | 10.0 | 10.6 | 72 | 77 | 24.8 | 26.3 |
2000 | 10.3 | 10.6 | 74 | 77 | 28.4 | 29.2 |
2200 | 10.5 | 10.6 | 76 | 77 | 31.8 | 32.1 |
2400 | 10.6 | 10.7 | 77 | 77 | 35.0 | 35.4 |
2600 | 10.5 | 10.8 | 76 | 78 | 37.6 | 38.7 |
2800 | 10.3 | 10.8 | 74 | 78 | 39.7 | 41.6 |
3000 | 9.8 | 10.8 | 71 | 78 | 40.5 | 44.6 |
3200 | 9.7 | 10.4 | 70 | 75 | 42.7 | 45.8 |
3400 | 9.4 | 10.2 | 68 | 74 | 44.0 | 47.7 |
3600 | 9.3 | 9.7 | 67 | 70 | 46.1 | 48.1 |
3800 | 8.9 | 9.3 | 64 | 67 | 46.6 | 48.6 |
4000 | 8.5 | 8.9 | 61 | 64 | 46.8 | 49.0 |
So, what is the most useful interpretation of this? Possibilities:
A) In the OEM Type 1 1600cc engine, the dual port has more maximum torque (and HP) than the single port heads at all RPMs. They are close in performance at 2200-2400 RPM (where the SP is near its peak), but the dual port performs significantly better above and below that. The torque curve on the DP engine is relatively flat from 1600 RPM to 3000 RPM. (This is pretty much a direct reading of the chart info.)
or
B) That data isn't applicable to Type 1 engines in aircraft (due to induction differences, different camshafts, etc). The single port performs better in aircraft, especially at low RPMs
or
C) At 1600cc dual port engines may provide more torque and power in aircraft installations, but single port heads are still preferable for other reasons (BSFC, strength, cooling, etc)
And, any implication for engines of larger displacement?
I'm pretty sure nothing here is new, but it is the first time I'd seen it.
Mark
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